In planar, wafer based mass production of IR detector matrices (hereinbelow referred to as “detectors”) having read-out electronics (hereinbelow referred to as “IC” or “electronics”), two main principles have bee employed.
1. The IC is manufactured to a finished state, and then the detector is manufactured on the IC. The detectors are built onto the IC wafers, an advantage with this approach is that so called IC-foundries can be used, which represents a very cost efficient manufacturing of the electronics wafers. A disadvantage is that there is a very restricted selection of materials and methods that are usable for the manufacturing of the detectors, because there is an upper temperature limit of about 400° C., above which the electronic will be damaged. This makes the manufacturing of detectors having optimal performance more difficult.
2. Overlapping IC and detector manufacture. I.e., at the end of the process for making the IC, detector manufacture is started on the same wafers. The advantage with this approach is that there is a greater freedom of selecting materials, methods and temperatures for the manufacture of detectors having good performance. A disadvantage is that the IC wafers cannot be manufactured in standard IC foundries, because they have very strict demands on a the process of manufacturing to be standardized in order to be able to maintain the quality in the processes. An example of a prior art processes can be found in EP 0 534 768 Al (Texas Instr.).